A few months ago I introduced my latest cheap classic, a 1975 MG B roadster. I have no firm plans as to how long I will own it but thought it might be interesting to others to document what fixes it needs and how I end up using it. First on the priority list was the replacement of the wonky transmission. Follow along as we swap that and discover a few quirks of B ownership.

The first quirk I discovered was before even attempting the transmission swap. I have owned a couple other convertibles including a pair of Triumph Spitfires and a TR8. The tops have been easy and painless to fold up and down. The MG B with the Michelotti top is not nearly as straight forward as one would expect. It can also be damaged by improper folding so I am glad it did not attempt to drop the top right after buying the car. Here is a video of the instructions for those morbidly interested. For everyone else I would recommend buying a Triumph if an easy folding top is a priority for your little British car.

I suspect the gearbox that came in the car had a bad syncro on third gear. This meant one had to double de-clutch to get into third and if one was to let off the gas while in third it would pop out of gear. The seller disclosed this up front and it was reason why the car was priced so cheaply. The drive home was enough to convince me I did not want to live with it as is for the summer. Luckily I was able negotiate the inclusion of a spare transmission with the car purchase. It was untested and filthy however. The MG B is relatively mechanically robust so I felt I could gamble and install it as is. The fall back plan would be rebuilding one or the other in the case that they were both bad.

I did feel it, at least, it needed a bit of a clean first.

First up was removing the hood for ease of access. This is not strictly necessary as one could tie it upright to a garage rafter. Unfortunately my garage does not have any exposed beams. It is not a particularly hard process to remove the hood with only a few easy to reach bolts. It was a little cumbersome to do solo but I managed.

I should probably buy a workshop manual for the car but according to all the online resources the easiest way to remove and install the transmission is as a unit with the engine. After poking my head under the car I can see why. It would near impossible to line up the transmission with the engine and bolt it together. So next up is draining and removal of the radiator.

Obviously well overdue for a coolant change as this is what came out of the radiator.

The fan is looking rather shabby. I cleaned it up and gave it a coat of black paint. I neglected to take an after photo so only this before shot will have to suffice. Please imagine it shiny and black as the end result.

New parts. The previous owner had installed poly bushes last summer in the front suspension.

Here is another quirk of the MG B. The battery is under a panel, behind the passenger seat. It can make for tight clearances and I have heard that sparks can fly when removing the cables or battery. Still this is an improvement on the early Bs which had a dual 6V battery configuration.

We will skip a pile of boring work (disconnect hoses, driveshaft, remove alternator, etc, etc) and get right to taking the engine out. The factory recommended using the two rather small looking rocker cover bolts as the mounting points for lifting the engine. The 1.8L four cylinder is a surprisingly heavy lump of metal and the transmission adds more weight so I wrapped a chain around it instead. The oil cooler and lines ideally should have been removed before pulling but I surmised that I would likely to damage them so they came along with the engine.

With the engine and transmission out, a reasonably spacious engine compartment remains. A previous owner did some odd rewiring of the fuse box (next to the coil). It all appears to work well so I am going to leave it in place until it gives me reason to think otherwise. You can see some of my labeling in the engine compartment. I tend to label everything I can with painter’s tape as it does not leave a sticky residue when removed. I also like to take piles of photos of the original configuration. I find it keeps the inevitable head scratching to a minimum when putting it all back together.

The replacement transmission swapped onto the motor with minimal drama and is ready to be dropped back in.

Luckily my engine crane has a large range of motion as the engine/transmission needs to get fairly high off the ground to go in at an angle. It also helps to have the rear wheels of the car jacked up.

Here is another MG B quirk. The transmission needs to be filled from inside the car. There is a rubber plug behind the center console that needs to be pulled out. Then with a bit of groping around in the dark you find the dipstick for the transmission.

A length of clear hose and a funnel aid in adding oil to the gearbox. Apparently spilling oil all over the passenger side of the your car is a rite of passage for B owners. I only managed to get a drop on the passenger seat which wiped up easily. A significant spill on the carpet would not have had such a happy ending.

Pulling an engine/transmission and reinstalling it is a big job comprised of many, many smaller ones. Some are easy but require attention to detail, reconnecting the spark plugs in the right order, while others are frustrating due to access constraints, re-connecting the drive-shaft where the bolts are tightened a fraction of a turn at a time. I finally got all the details sorted and turned the key for the first time only to be confronted with a no start situation. Jumping into troubleshooting mode I found the engine was getting spark when cranking over and as well as fuel. I knew I had not touched the timing and really any engine should at least run poorly if it is getting fuel and spark.

After some contemplation and perhaps a few four letter expletives I realized that the engine was starting but only very briefly. As soon as the starter was released the engine would cut out. A short while later I located an ignition wire that should have been connected to the coil. Restoring that connection brought the car back to life and running condition. I have heard since that this wire can often be knocked out of place when an oil change is occurring leading to a frustrating no start situation. I seem to be learning a great number of MG B quirks in a short period of time.

The initial drive around the block showed promise. All gears were accessible and appeared to work. I did, however, almost manage to shift from 1st into reverse instead of second at speed. The above shift pattern means one has to be mindful shifting to second. Ironically it can be tough to find reverse when you actually want it.

A longer shakedown run outside the city limits again went very well. A yellow Canola field offers an interesting contrast to the blue paint. As I build trust in the car I will continue to take it farther afield so follow along at a later date to see where the Beater B goes this summer.

It’s a little more involved (IIRC), to swap the black for the chrome bumpers than just unbolting the one and installing the other. The sheetmetal behind the rubber bumper cars is slightly different from the early cars.

These Bs don’t come up for sale all that often here in north Florida, 90% seem to hit Craigslist between May and October….then go back into storage. Yet every time I see 1 for sale I’m tempted to contact the seller. I owned a 72 Spitfire and a 60 TR3 “in a previous life”. Those come up for sale even less often than MGs, though.
Unfortunately, I don’t have the space to work on a car, or the space to store it when it’s not driveable.

As Howard says the process isn’t as simple as one would imagine. To do it properly is a reasonably big job. There are body panels that need to be replaced and painted. That would be decent money all by its self. The chrome parts are in demand as well. Ironically I have chrome bumper parts of a MG Midget sitting around but they are much too narrow.

A good read! I don’t have a lot of MG experience, although I have a lot of seat time in my Alfa Spider. The difference between the two seems, well, farther than I thought. For example, putting the top up or down on the Spider is roughly a 30-second operation involving two levered clamps at the windshield. Note that this is NOT to say that Alfas don’t have quirks of their own….

While the Miata was designed with the similar-roofed Lotus, the convertible top on the Miata was specifically chosen for the ability to easily raise and lower it. With the addition of a handy strap, I can close it in 20 seconds, and down is 2 latches and try not to slam the glass!
Enjoy your Beater B. A beater is better than a pristine model, because you will actually use and enjoy it rather than pampering it.

1) Convertible top — a convertible needs to have a power top for me — one of the great joys in life is that combination of hydraulic-pump whine with the sudden lifting of the roof when you turn the knob counterclockwise on the dash of my Valiant.
2) Nice you can at least just bolt up your transmission, tho’ I guess I’m thinking more about the need to use a dial-meter to align a Studebaker clutch bell housing to avoid a similar case of jumping-out-of-third (or cracking the flex-plate in an Automatic) when replacing the entire setup.
3) You had that all apart and didn’t renew the clutch and pilot bearing at the same time? Wow! Brave man!

Wow ! you trusted that anything was done correctly on a cheap LBC ?! .

FWIW, the fan needs to come back out for thorough cleaning to bare metal then be re sprayed yellow because they get tiny cracks that you’ll never notice on a black fan then when the blade rips off as you’re howling up towards fourth gear and pokes through the bonnet, you’ll understand why .

The gearbox needs _DETERGENT_ENGINE_OIL_ and I always find fully synthetic makes for the best shifting . GEAR OIL WILL KILL IT .

Add a $6 Harbor Freight rare earth magnet to the engine and tranny drain plugs,set the valve lash (it’s always wrong) and base ignition timing to 10° BTDC and it’ll be much more fun to drive until you tire of it .

The steering rack needs 90W gear oil, I remove the square cover plate to add it, change the boots as soon as one tears to avoid $ hassles .

Remember : it’s a SPORTS CAR not a RACE CAR so drive it hard but don’t beat it to death and you’ll be happier .

-Nate
who sort of misses his 1967 MGB GT but it didn’t want to stay on the road at the speeds I liked driving it

The sulfur in gear oil will remove the moly synchro surfaces on the gears.

David Saunders

Posted July 12, 2017 at 7:04 AM

I researched this on various MG sites. Gear oil suggestions seemed rather mixed for synthetic. A lot of folks suggested the same as the motor – Castrol GTX.

Sounds like I should be repainting that fan yellow!

-Nate

Posted July 12, 2017 at 7:49 AM

The mail thing is to use good quality ENGINE OIL not gear oil, whatever stuff ‘because it’s a manual tranny’ .

Think for your self her using real world experience and tech ~ many MG Enthusiasts still insist you shouldn’t upgrade to a breaker less ignition, only use SHELL lubricants because that’s what it says on the oil cap and other such foolishness .

If you want to drive it daily and enjoy it, use the best high tech modern stuff you can ~ fully synthetic lubricants, radial tires (yes some boob insist MGs handle better on Bias Ply tyres etc……

Use your brain here .

OBTW : open the spark plugs up to at least .035″ and feel the extra power .

Easiest way to access reverse…select second gear (stops the shaft from moving which causes the slight grind on entering reverse), go to neutral, then slap the gearshift to the left and pull down. Guaranteed to slip into reverse, quietly, every time. Mine was a 1968 B. And yes, the convertible is a minor pain. But I had a factory hard top too, a real pain to remove.

You can take the gear box out the bottom and leave the engine alone. As the Brit’s would say, it’s a bit fiddly, but beats engine removal. A lift is almost required

I liked removing Healey and Triumph gearboxes through the top. I had my first 100-4 up in the air and had removed everything attached to the gearbox. They were big and heavy. I picked it up to step down to the floor, when the door shut and latched. Time to back up and start over. I didn’t have the poo to leap over the door with the gearbox.

Brings back memories! I did my first engine pull on a B (and first clutch replacement). I used a come-a-long on a tree branch overhanging the driveway (before I knew what a shade-tree mechanic was). My room mate at the time bet me $10 I would never get it all back together. He lost. It looks as though the previous owner had done battle with the Prince of Darkness…

I love write-ups like this that show the DIY nitty-gritty of jobs that most people are not knowledgeable or brave enough to undertake themselves. Congrats on a job well done; this car is now worth a lot more money, but regardless, now you can enjoy driving it the way you wanted to.

I had two MGB’s when I was younger – a ’74 and a ’76 which looked pretty much exactly like the one in this write-up. Most entertaining cars I ever owned. Drive it till it breaks-down (which was usually only a couple of days with the ’74), fiddle with it till it runs again, drive it till it breaks down, rinse and repeat.

The quirk I remember most (in addition to the odd battery location) was the location of the fuel pump under the floorboard behind the passenger seat. I remember it would “tick” when you turned the switch on, and you started the car when the ticking stopped. It would sometimes get gummed up and starve the engine of fuel. I used to carry a hammer around behind the seat and when the engine started sputtering, I’d reach over, bang on the floorboard behind the passenger seat a few times, and that usually freed things up.

I also remember being told by a veteran MG owner when I bought my first B, “If your MG ever stops leaking oil on your garage floor you better fill it up because t’s out.”

Use engine oil in the gearbox same reason as with Hillmans the sulphur eats the bronze syncros or as a Hillman racer told me recently 50/50 auto trans fluid engine oil mix cuts drag for more power, worn thrusts is why it jumps out of gear on overrun I have a spare Superminx gearbox in my carport pulled out for that reason, those MGBs are cool little cars and easy to work on and fix if they go wrong.

I’ve never been partial to MGs but now that I read your story and the video on folding the top, forget about it. At least it is not like what came before where you had to build the frame.
The tops on my Austin Healey BJ8 and my Fiat 124 Spider are very easy to lower or raise.